Associativity

We'd like to write slightly bigger programs. We probably want to nest function calls. How can we do that, with Haskell's unusual syntax?

As a silly example, let's try to negate a boolean twice using the not function. Think about how you would do that.

You may have thought about doing it like this:

not not True

That doesn't work, though, because "function application" associates to the left. What does it mean? The expression we wrote above is equivalent to:

(not not) True

This cannot possibly work, because the first not expects an argument of Bool (and instead it received a function), and the second not doesn't have any argument.

Use the parentheses appropriately to write the call of not twice on True. Use the REPL to experiment.